19
3. Dimensions
29
27
27
33
Housing
Housing
Thermistor
Thermistor
Thermistor
Thermistor
Window
Window
Lead wire
Lead wire
Evaporator Pipe
18
R4.3
5
1
5
(mm)
FROST DETECTING SENSOR
FD SENSOR
1. Application
Any frost-free system found in domestic and commercial fridge-freezers,
vending machines, ice-makers, etc.
2. Features
Simple detecting principle
Highly sensitive
Ease of assembly
Replaces less-efficient conventional sensors
The FD Sensor has been developed to detect the level of accumulated frost
on the evaporator in frost-free systems, such as those found in domestic
fridge-freezers. It helps to eliminate unnecessary defrost cycles and also
increases the energy efficiency of the system.
4. Findings from studies carried on the FD Sensor
5. Specifications
6. Reliability
Climatic test properties
7. Mechanical properties
NTC Thermistor characteristics(only for reference)
Power Consumption
No. of defrost cycle completed
Conventional Fixedtime defrost system
Defeost system with FD Sensor
Improved efficiency
74.16KK Whr/month
65.6KK Whr/month
12%
9 times/week
Once/week
Criteria
Dry heat
Test
Test Conditions
In air at 100 C for 1,000hr.
Between
40 C and
75 C for 10,000 cycles.
In air at
55 C for 1,000hr.
95% RH at 40 C for 1,000hr.
Cold
Damp heat
Thermal shock
Deviation of resistance at 25 C from the original value
after test within
2% and deviation of B value(B25 85)
from the original value after test is within
1%.
Criteria
Free Fall
Test
Test Conditions
3 natural drops from 75 cm high
JIS C2571 Item A
40 N for 10 seconds
Robustness of
termination
Vibration
Deviation of resistance at 25 C from the original value
after test within
2% and deviation of B value(B25 85)
from the original value after test is within
1%.
Study (A)
A 12% of energy saving in a 420 liter domestic frost-free fridge-freezer was found by one of the major Japanese refrigerator manufacturers by the following test
procedures.
Test Procedure
The power consumption measurement was carried out in accordance with JIS C9607 power consumption test, item B (
ISO8561).
The test procedure was extended to one week to determine the full advantage of the defrost system using the FD Sensor.
Study (B)
Evaluation of the FD Sensor in a 130 liter domestic frost-free fridge-freezer was made by another Japanese refrigerator manufacturer.
They obtained an energy saving of over 10% using the same test method as in 5(A) above but including the opening and closing the fridge-freezers
doors.
Study (C)
FD Sensor
1) Environmental Temperature range :
40 C
80 C
2) Operating temperature range
:
40 C
5 C
3) Sensitivity
: 4 C 12 C
(Difference in temperature measured by both NTC Thermistors when no frost is recognized.)
Evaluation of the FD Sensor in a 400 liter domestic frost-free fridge-freezer made by a Japanese refrigerator manufacturer shows an energy saving of over 10%.
Measurement of this energy saving was made using the test method specified as in 5(A) above.
1) Nominal Zero power resistance
: R25 10k
3%
2) Rated B value
: B25 85 3435K
1%
3) Absolute difference between the two NTCs :
0.2% or
0.05 C at 25 C
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